Add new GrResourceCache::purgeUnlockedResources variant

TBR=bsalomon@google.com
Change-Id: I05bef1f8a271474db878a046cc1f6ac7b60a15f1
Reviewed-on: https://skia-review.googlesource.com/116801
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
5 files changed